Kosei Tanaka
Kosei Tanaka is a Japanese professional boxer. He is a three-weight world champion, having held the WBO flyweight title since 2018; the WBO mini-flyweight title from 2015 to 2016; and the WBO junior-flyweight title from 2016 to 2017. Upon winning his first world title in only his fifth bout, he became the fastest Japanese fighter ever to become a world champion. Along with Vasyl Lomachenko, he is also the fastest ever fighter to win titles in three weight-classes, having accomplished the feat in only 12 bouts.
As of July 2020, he is ranked as the world's best active flyweight by The Ring magazine, BoxRec and the Transnational Boxing Rankings Board.
Career
As a child, Tanaka suffered from Legg–Calvé–Perthe disease. Despite this, he took up boxing and won four national tournaments competing as an amateur in the junior-flyweight division. At the continental and international level he was a quarter-finalist at the 2012 Youth World Championships and a silver medalist at the 2013 ASBC Asian Confederation Youth Boxing Championships.Mini-flyweight
Tanaka turned pro at the age of 18 in 2013. In November 2014, Tanaka defeated previously unbeaten Ryuji Hara via tenth-round technical knockout to win the OPBF mini-flyweight title. In his next fight, Tanaka decisioned Julian Yedras to win the WBO mini-flyweight title. Tanaka holds the Japanese record for winning a world title in the fewest fights, surpassing the previous record held by Naoya Inoue of six fights. Tanaka's only title defense at mini-flyweight came against Vic Saludar, whom he knocked out in round six after a left hook to the body. Saludar knocked down Tanaka in round six, and was ahead on all scorecards prior to the stoppage.Junior-flyweight
In December 2016, Tanaka challenged former mini-flyweight title holder Moisés Fuentes for the WBO junior-flyweight title. Tanaka dominated Fuentes, dropping him in round five before referee Raul Caiz Jr stopped the fight, giving Tanaka a TKO victory. With the win, Tanaka became a two-weight world champion in just eight fights. Tanaka's first defense came against prospect Ángel Acosta. The former won a wide unanimous decision and dropped Acosta once. Acosta had won all 16 of his previous fights by knockout.Tanaka's second defense took place in September 2017 against little-known fighter Palangpol CP Freshmart. Tanaka was a huge favorite going into the fight, but Palangpol would prove to be Tanaka's toughest challenger so far, dropping the defending champion once in the first round and trading back-and-forth combinations for the rest of the bout. After a thrilling fight, Tanaka would finally gain the upper hand in round nine, as he knocked down Palangpol and continued to land big combinations as the challenger struggled to connect. Eventually, the referee stepped in and stopped the fight at 1:52 in round nine.
Tanaka had previously sought a unification bout against WBA titleholder Ryoichi Taguchi in December, but injuries during the fight against Palangpol would prevent him from fighting on that date.
Flyweight
In December 2017, Tanaka vacated his junior-flyweight title to move to the flyweight division. In September 2018, Tanaka defeated Sho Kimura to capture the WBO flyweight title, equalling Vasyl Lomachenko's record of becoming a three-weight world champion in just 12 fights.Personal life
Tanaka balanced professional boxing with school and in 2019 graduated with a degree in economics from Chukyo University. He is the cousin of Japanese figure skater Yuhana Yokoi and younger brother of amateur fighter Ryomei Tanaka.Professional boxing record
| No. | Result | Record | Opponent | Type | Round, time | Date | Location | Notes |
| 15 | Win | 15–0 |  Wulan Tuolehazi | KO | 3, 2:29 | 31 Dec 2019 |  Ota City General Gymnasium, Tokyo, Japan | Retained WBO flyweight title |
| 14 | Win | 14–0 |  Jonathan González | TKO | 7, 2:49 | 24 Aug 2019 | Takeda Teva Ocean Arena, Nagoya, Japan | Retained WBO flyweight title |
| 13 | Win | 13–0 | Ryoichi Taguchi | 12 | 16 Mar 2019 | Memorial Center, Gifu, Japan | Retained WBO flyweight title | |
| 12 | Win | 12–0 | Sho Kimura | 12 | 24 Sep 2018 | Takeda Teva Ocean Arena, Nagoya, Japan | Won WBO flyweight title | |
| 12 | Win | 11–0 |  Ronnie Baldonado | TKO | 9, 2:26 | 31 Mar 2018 | International Conference Hall, Nagoya, Japan | |
| 10 | Win | 10–0 |  Palangpol CP Freshmart | TKO | 9, 1:29 | 13 Sep 2017 | Edion Arena, Osaka, Japan | Retained WBO junior-flyweight title |
| 9 | Win | 9–0 | Ángel Acosta | UD | 12 | 20 May 2017 | Takeda Teva Ocean Arena, Nagoya, Japan | Retained WBO junior-flyweight title |
| 8 | Win | 8–0 |  Moisés Fuentes | TKO | 5, 1:52 | 31 Dec 2016 | Memorial Center, Gifu, Japan | Won vacant WBO junior-flyweight title |
| 7 | Win | 7–0 | Rene Patilano | KO | 6, 2:23 | 28 May 2016 | International Conference Hall, Nagoya, Japan | |
| 6 | Win | 6–0 | Vic Saludar | KO | 6, 2:15 | 31 Dec 2015 | Aichi Prefectural Gymnasium, Nagoya, Japan | Retained WBO mini-flyweight title |
| 5 | Win | 5–0 | Julian Yedras | UD | 12 | 30 May 2015 | Park Arena, Komaki, Japan | Won vacant WBO mini-flyweight title |
| 4 | Win | 4–0 | Ryuji Hara | 10, 0:50 | 30 Oct 2014 | Korakuen Hall, Tokyo, Japan | Won OPBF mini-flyweight title | |
| 3 | Win | 3–0 | Crison Omayao | 1, 1:55 | 20 Jul 2014 | International Conference Hall, Nagoya, Japan | ||
| 2 | Win | 2–0 | Ronelle Ferreras | UD | 8 | 16 Mar 2014 | International Conference Hall, Nagoya, Japan | |
| 1 | Win | 1–0 |  Oscar Raknafa | 6 | 10 Nov 2013 | International Conference Hall, Nagoya, Japan |